onRepeat not getting getting called when time is close to a multiple of the duration of a tween

[mdatsev]

When the time lands on values that are close (but not exactly equal) to a multiple of the duration of a tween, the onRepeat call will not be called.

Here is an example:

gsap.to({ x: 0 }, {
  x: 100,
  duration: 3,
  repeat: 4,
  onRepeat: () => {
    console.log("Repeat called!");
  },
});

for (const time of [
  0, 1, 2, 3, 4, 5, 6.0000001, 7, 8, 9.0000001, 10, 11, 12.5, 13,
]) {
  gsap.updateRoot(time);
}

In this case we see only 2 console.log's (when the time reaches 3 and 12.5 - which are either equal or after the repeat time), but we expect 4 console.log's (also when the time is close to 6 and 9).

Here is a full reproduction example: https://codepen.io/mdat/pen/wvLOMwV
And here is an example with other slightly changed time values which works as expected (called 4 times): https://codepen.io/mdat/pen/qBzvNGp

This might not seem important for a real-world application, but if the framerate is consistent and we happen to choose a duration which is multiple of it, it is quite possible to sometimes land on a value this close to it and get unexpected behavior. Which happened to our team and it was quite difficult to debug.

[jackdoyle]

Yes, there is rounding that occurs internally in order to protect against a bunch of edge cases (trust me, it's a good thing). So I'd recommend applying similar logic in your code. For example:
https://codepen.io/GreenSock/pen/XWLGprr?editors=0010

[mdatsev]

Hello, thank you for the quick response and suggestion!

Unfortunately I don't think this method will work in general. We have some durations which are calculated from other parameters and they are not always integers. See here for example:

https://codepen.io/mdat/pen/OJeqWrd?editors=0012

If we set the scale to 1 it works, but if scale up the duration and times by a factor of 1.1, which should in theory keep the same behavior the bug still reproduces. Do you have any suggestions for a general workaround?

[jackdoyle]

Sure, you're just doing the correction at the wrong spot. Here's an even easier solution:
https://codepen.io/GreenSock/pen/vYqPwxO?editors=0012